Oil and gas hydrocarbons are naturally occurring in some subterranean formations. A subterranean formation containing oil or gas is sometimes referred to as a reservoir. A reservoir may be located under land or off shore. Reservoirs are typically located in the range of a few hundred feet (shallow reservoirs) to a few tens of thousands of feet (ultra-deep reservoirs).
In order to produce hydrocarbons, a wellbore is drilled through a hydrocarbon-bearing zone in a reservoir. In a cased-hole wellbore or portion thereof, a casing is placed, and typically cemented, into the wellbore providing a tubular wall between the zone and the interior of the cased wellbore. A tubing string can then be run in and out of the casing. Similarly, tubing string can be run in an uncased wellbore or section of wellbore. As used herein, “tubing string” refers to a series of connected pipe sections, joints, screens, blanks, cross-over tools, downhole tools and the like, inserted into a wellbore, whether used for drilling, work-over, production, injection, completion, or other processes. Further, in many cases a tool can be run on a wireline or coiled tubing instead of a tubing string, as those of skill in the art will recognize. A wellbore can be or include vertical, deviated, and horizontal portions, and can be straight, curved, or branched.
During completion of an open-hole wellbore portion, a completion tubing string is placed into the wellbore. The tubing string allows fluids to be introduced into, or flowed from, a remote portion of the wellbore. A tubing string is created by joining multiple sections of pipe together, typically via male right-handed threads at the bottom of an upper section of pipe and corresponding female threads at the top of a lower section of pipe. The two sections of pipe are connected to each other by applying a right-hand torque to the upper section of pipe while the lower section of pipe remains relatively stationary. The joined sections of pipe are then lowered into the wellbore. The process is referred to as “making up” a string. The tools used in the string are often assembled, or made-up, on the rig floor. In fact, this may be required for lengthy tools inserted by a standard rig.
It is typical in hydrocarbon wells to “set” or actuate a downhole tool, such as expansion tools, packers, bridge plugs, gauge hangers, straddles, wellhead plugs, cement retainers, through-tubing plugs, etc. Setting of tools is often done in conjunction with other wellbore operations. For example, a tubing string is run into a wellbore to hang an expandable liner, cement around the liner, and then expand the liner. The string is then disconnected from the installed liner and hanger and retrieved to the surface.
In a typical liner hanger tool string, the tensile load and rotational load on the string is carried through an internal mandrel. The relative motion required for setting the tool, and the transfer of setting loads, is typically done using a non-load bearing external cylinder or sleeve. For example, commercially available from Halliburton Energy Services, Inc., is a Versaflex (trade name) running tool having such a configuration. If the tools are made-up, such as in two halves, on the rig floor, this arrangement is cumbersome, requiring make-up of the mandrel assembly and make-up of the external cylinder assembly, including seals. For most applications, the use of the assembled parts with seals also requires a pressure test prior to use. Such tests can be awkward, time-consuming or even impossible on the rig floor.
Consequently, there is a need for an improved manner of design, assembly and use of running tools.